1. Field of the Invention
This invention relates to a safety device for gas welding, and more particularly to a safety device for gas welding which is provided between a gas supply-side and a burner torch to prevent the explosion of the gas supply-side due to counter-flow and back-fire of the gas.
2. Description of the Prior Art
Usually, in gas welding, when oxygen gas itself or a mixture of oxygen gas and inflammable gas flows backward from the burner torch-side to the direction of the inflammable gas supply source of acetylene gas and the like, under the burning state or the nonburning state, then the supply source of inflammable gas will explode. Therefore, certain methods for preventing the explosion of the inflammable gas supply source by providing a safety device between the burner torch and the inflammable gas supply source are known.
One known safety device is in the form of a pipe joint connecting the flow path of a hose or a pipe and the like, and devices by which the counter-flow and the back-fire of gas are prevented by means of a check valve are used. In these safety devices, however, the counter-flow and the back-fire of gas are prevented when they take place, but the connections of the hose and the like with the safety device is held and never released, so that there remains a danger or explosion.